Breast cancer is the leading cause of cancer-related deaths for women in the world. It is the second most common cancer in females in India and the early detection and treatment improve prognosis and survival rate, motivating the need for finding out novel non-invasive methods for early diagnosis of this disease. Presently, biopsy is the only method which confirms the diagnosis and different grades of cancer. Being an invasive method, it is time consuming and often uncomfortable for the patient. Moreover, the negative biopsy rate is significantly high, especially in screen detected and non palpable cancers suggesting that better molecular diagnostic techniques are needed to replace or compliment current biopsy techniques. Tissue characterization by pathologists for ER, PR and HER 2/Neu status and axillary lymph node status are the most important prognostic factors and 90% of those patients without nodal involvement have no further breast cancers detected in their lifetime. Presently, there is no established non-invasive test for confirming the axillary node status. Axillary nodal status is of major importance from a therapeutic and prognostic point of view. Moreover, majority of patients end up doing chemotherapy due to lack of reliable markers. Chemotherapeutic drugs currently used are also not specific to breast cancer. Therefore it is imperative to find novel biomarkers for early and accurate diagnosis and prognosis in breast cancer sparing the majority of patients from undergoing an axillary dissection. Such molecular signatures can also lead to good prognosis and help develop novel targeted treatments. Moreover, such an approach can accurately identify subgroups of patients who will really benefit from cytotoxic chemotherapy with its debilitating side effects.
The diagnosis of breast tumor starts with the screening techniques to confirm whether a lump is present or not. The noninvasive examination techniques existing are mammography, ultrasound or MR imaging which determine the presence of any tumors and also detect tumor size, invasion etc. To further confirm the tumor diagnosis and grading, Fine Needle Aspiration and Cytology (FNAC), core biopsy and excisional biopsy is required. Additional testing may include genetic screening that test for the status of hormones like ER, PR, and genes like HER2/neu etc. Chemotherapy is currently used for all cases of Infiltrating duct carcinomas of breast.
Mammography and ultrasound may identify a potential area of concern. MRI imaging requires injection of a dye, the side effects of which are not yet proven. Fine Needle Aspiration Cytology (FNAC) is not always as reliable as surgical biopsies in producing a conclusive diagnosis. Immunohistochemical analysis of ER, PR, HER2/neu, BRCA and PTEN requires lot of time to arrive at any final conclusion of disease progression. The available diagnostic methods present in the market are not up to the expectation that one can diagnose the early stages of disease and therapeutic measures can be optimized to completely prevent and cure the tumor at right time. These above mentioned imaging tools are not sensitive methods to detect early molecular changes occurring in the cell during initiation of the cancer. Tissue embedding, sectioning, staining are all cumbersome procedures and time consuming. Moreover, staging could be determined only after getting the final histopathology report and extensive metastatic workup. No existing technologies are there for more accurate staging of the disease for identifying suitable patient sub groups to tailor systemic treatment. *There are no proper fast and accurate molecular diagnostic tool for pathologists till now for accurate staging and grading. As far as current chemotherapy regimens are concerned, no targeted therapy is currently used.
Biomarkers constitute the most important field in cancer diagnosis. Cancer biomarkers are especially useful for early detection or diagnosis of the disease. Biomarkers can be used to screen patients, for classifying the different stages or grades of cancers and to predict prognosis and resistance to therapy. A tumour marker can be produced by tumour itself or by the body as a result of the disease. These biomolecules are quite often produced in abnormally large numbers in the cancerous tissues and often secreted to body fluids like blood, serum, urine etc. To identify molecular changes setting-in much before the disease initiation and progression, development of molecular biomarkers is extremely important.
MicroRNAs are small RNAs of 22-25 nucleotides in length with a major role in gene regulation. Since they are highly conserved between the genomes of related species and show a characteristic evolutionary divergence, computational analysis of miRNAs would augment the experimental analysis to identify those which are involved in the regulation of common genes and pathways leading to the development of cancer. Recently, oncomiRs, special classes of non-coding microRNAs are found to be associated with a large number of cancers. Consequently impaired miRNA expression is implicated in various tumours. This class of novel non-coding RNAs or microRNAs is expected to eventually identify previously unappreciated tumour suppressors and oncogenes and also address many questions about the origin, development and progression of breast cancer. Many studies have shown a deregulation with respect to the expression of these small RNAs in many tumours. It is imperative to know the expression profile of these microRNAs which would help us to classify, and associate these miRNAs with different stages and grades of tumours so as to develop them as novel biomarkers of various cancers. Thus the expression profiles could be used for classification, prognosis and diagnosis of human malignancies
Present National and International Knowledge on the Utility of this Invention:
Disease in whichS.Name of theobjectives ofinvestigation isNo.InventorinvestigationdoneName of biomarkers1.Eugene M. S.Detection of inInfectious diseaseTissue specific miRNA(U.A.E.)vivo cell death2Talyor D. D.DiagnosticDiagnosis ofExosome associated miRNA(U.S.A.)markercancer3.Chen, Jian-WeiPost treatmentCancerhsa-miR-137, hsa-miR-372,(Taiwan)survival inhsa-miR-182*, hsa-miR-221,cancerand hsa-let-7a4.Fischer T. J.Early stageBreast CancerBiomarkers of the invention(U.S.A.)Breast cancerare proteinsprognosis5.Dmitrovsky, E.miRNA asBreast cancerMiRNAs are downregulated:(Hanover, NH,biomarker ofhsa-miR-451, hsa-miR-143US)human breastand hsa-miR-145.cancer6.Croce C. M.Diagnosis,Breast cancermiRNAs are upregulated:(Columbus, OH,prognosis andhsa-miR-141, hsa-miR-200b,US)treatment ofhsa-miR-200c, hsa-miR-221,breast cancerhsa-miR-222 and hsa-miR-21.miRNAs are Down regulated:hsa-miR-125b-1, has-miR125b-2, has-miR-145, hsa -miR-21,has-miR-155, hsa -miR-10b
Other Examples of Similar Studies:
OncomiRs are a special class of non-coding microRNAs found to be associated with a large number of cancers. Consequently impaired miRNA expression is implicated in various tumours. Various in vitro and in vivo studies have implicated an active role of microRNAs in breast cancer. Many reports on microRNAs indicated their role in cell proliferation and apoptosis growth and migration (1 & 2) suggesting that deregulation of these microRNA could lead to proliferative diseases like cancer. Also studies have shown that microRNA cluster mapped to the hotspot areas of the genome that are prone for cancer mutations (3 & 4). Their expression patterns show a general trend of down regulation in human cancer samples (5) indicating that most of them function as tumour suppressors. Though many profiling studies have revealed a different signature of the cancer samples compared to normal tissues, very few studies have been conducted which elucidates the functional role of each of these microRNAs. In breast cancer, microRNA miR 206 was found to inhibit the function of estrogen receptor gene ESR1. Later, it was found to be targeted by a set of microRNAs like miR 18a, miR 18b, miR 193b and miR 302c (6 & 7). CyclinD1 which is over expressed in majority of the cancers was identified as a direct target of miR 17-5p (8). Under expression status of miR 125a & b in HER 2 positive tumours indicated their role as a tumour suppressor of this gene. Analysis of triple negative (ER, PR and HER2/Neu) breast cancer patients showed that expression levels of miR 210, miR 21, and miR 221 play a significant role in the primary breast cancer vs normal samples (15). Down regulation of miR 200 family members in highly metastatic tumours and their up regulation in mesenchymal cells which initiated mesenchymal to epithelial transition depicted its role in metastasis (10). Let 7, one of the founder members of microRNAs are usually under expressed in tumours. One of the studies revealed that their down regulation induced BTI-Cs (Breast—Tumour initiating Cells) for tumour initi ation, progression and metastasis and vice versa (11). MicroRNAs miR 21, miR 155 and miR 10b have been shown to play a role in tumour metastasis by targeting anti metastatic genes (12, 13,14). MiR-21 is over expressed in both male and female breast tumors compared with normal breast tissue and has been associated with advanced stage, lymph node positivity, and reduced survival time. Furthermore, existence of microRNAs either floating or in exosomes in the systemic circulation, has led to the possibility that such molecules may serve as biomarkers for early detection of cancers. Thus microRNA profiling is emerging as a powerful tool for diagnosis of breast cancer types, grades and stages. Although additional investigations are necessary to fully exploit the therapeutic use of miRNAs in breast cancer, there is increasing evidence that miRNAs have potential not only to facilitate the determination of diagnosis and prognosis and the prediction of response to treatment, but also to act as therapeutic targets and replacement therapies.
The drawback of these studies is that none of them was carried out in the specified stages of grades or subtypes of human breast cancer samples. Hence identifying the exact grade and stage of Breast Cancer is a boon for treatment of such kind of diseases.